S103 Weekly Cycle in NEXRAD Rain Rates

Sunday, 7 January 2018
Exhibit Hall 5 (ACC) (Austin, Texas)
Ryan Sullivan, NSF, Norwood, MN

NEXRAD (Next-Generation Radar) level-3 rain rate measurements for the summertime months
of 2004 –2013 were found on average to significantly correlate with a weekly cycle, attributable
to the rain rate intensification of evening storms produced by the aerosol pollution cycle. A
harmonic fit of the NEXRAD rain rate data suggests a sinusoidal weekly pattern with a
maximum peak residing during the middle of the work week throughout central to eastern U.S.
These findings are in agreement with the results produced by Bell [2008] which found a
significant aggrandizement of the TRMM rain rate data for the middle of the work week. Both
reports support the theory that aerosol pollution prevents rainstorm precipitation at early stages
in cloud formation allowing an increase in convection of water above the freezing isothermic
layer which creates large frozen hydrometeors; ultimately, leading to regional convergence and
an increase in rainfall [Bell 2008].
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